fix(mcp): do not let empty cdpHeaders from env override config file#39866

dgozman merged 2 commits intomicrosoft:mainmicrosoft/playwright:mainfrom

harrytran001:fix(mcp)-do-not-let-empty-cdpHeaders-from-env-override-config-fileharrytran001/playwright:fix(mcp)-do-not-let-empty-cdpHeaders-from-env-override-config-fileCopy head branch name to clipboard